An organic EL element is a light-emitting element using an organic substance as a light-emitting material, and is composed of a pair of electrodes (an anode and a cathode) and a light-emitting layer provided between the electrodes. When voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and then the holes and the electrons are recombined in the light-emitting layer to emit light.
The light generated in the organic EL element is output through the electrodes, and the light is used as a light source for display devices and illuminating devices. However, not all the light generated in the element is output, and a large part of the light is trapped in the element due to reflection and the like and thus is not effectively used.
In order to achieve a certain brightness that is required for a light source, there has been proposed a light-emitting device having an increased brightness in a normal direction in which a prism sheet having a structure for suppressing reflection and the like is arranged on a light extracting side of an organic EL element to increase the rate of the light output in the normal direction (for example, see JP 2007-5277 A).